As one type of image processing apparatuses as electronic equipment, an MFP (MultiFunction Peripheral) having a plurality of functions including copy function, printer function, scanner function and facsimile function has been known. Such an image processing apparatus requires many instructions and settings, and the settings are complicated. For this reason, a touch-panel display is often used for its operation console.
A touch-panel display is a device that detects a touch by a user, and it includes a display panel formed, for example, of a liquid crystal panel and a touch-panel placed on the display panel, for detecting a touched position. On the touch-panel display, software keys are displayed, and by touching the displayed keys, the user can enter instructions to the image processing apparatus. Even in such an image processing apparatus, however, for some functions (power on/off, power saving mode on/off, etc.), individual hardware keys are allocated and arranged on the operation console.
What is required of the operation console is not only having the function of entering instructions to the image processing apparatus. Since the user continuously looks at the operation console while he/she is operating the apparatus, the operation console may be regarded as the face of image processing apparatus. The impression of operation console decides the impression of the image processing apparatus as a whole. Therefore, to have the image processing apparatus considered to be a sophisticated, high-class apparatus, the operation console must have a high-class look.
As an example of an operation console using a touch-panel, Japanese Patent Laying-Open No. 2010-86236 (hereinafter referred to as '236 Reference) discloses a capacitance detection type touch-panel having protruding and recessed areas on its operation surface to prevent touching errors. On this touch-panel, recessed portions are formed at positions corresponding to various keys on the operation surface, to improve detection accuracy of key touching.
Sometimes, touch keys such as capacitance switches that can be operated by a light touch in the similar manner as the touch-panel are used as individual operation keys on the operation console. Such an operation key is structured, for example, as shown in FIG. 1. An operation key 900 has a key sheet 902 arranged on a housing (not shown) of an operation portion, and a circuit board 904 having LED elements 906 and 908 as light sources is arranged therebelow. Between key sheet 902 and circuit board 904, a transparent light guiding portion 910 that transmits light emitted from LED elements 906 and 908 is positioned.
Key sheet 902 is formed, for example, of polycarbonate with a colorant dispersed therein, having low transmissivity to visible light, and on its surface, figures representing various keys are printed at positions corresponding to respective keys. Specifically, the figure representing a key includes portions where ink is applied and other portions where ink is not applied. Light emitted from LED elements 906 and 908 passes through light guiding portion 910, enters key sheet 902 through an upper surface of light guiding portion 910, and emitted out from an upper surface of key sheet 902. In this manner, the figure printed on key sheet 902 is illuminated from the back side. Key sheet 902 has low light transmissivity at portions of the figure on which ink is not applied. If illuminated with light of a certain intensity or higher, however, it transmits light to some extent and, therefore, the figure is displayed in a manner visually recognizable easily, on key sheet 902.